<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            width: 100px;
            height: 100px;
            background-color: pink;
        }
    </style>
</head>
<body>
    <div>1</div>
    <div>2</div>
    <div>3</div>
    <script>
        var divs = document.querySelectorAll('div');
        divs[0].onclick = function () {
            alert(11);
            //1.传统方式删除事件
            divs[0].onclick = null;
        }
        divs[1].addEventListener('click',fn);//里面的fn 不需要调用加小括号

        function fn() {
            alert(22);
            divs[1].removeEventListener('click',fn);
        }
        //3.
        divs[2].attachEvent('onclick',fn1);
        
        function fn1() {
            alert('333');
            // divs[2].detachEvent('onclick',fn1);
        }


    </script>
</body>
</html>